Heat exchanger manufacturing method and diameter enlargement tool

ABSTRACT

A heat exchanger manufacturing method, including rolling a metal sheet into a roll shape to form a tube-shaped body, inserting the tube-shaped body through a through hole formed at a metal fin, and loosening the metal sheet that has been rolled into a roll shape to enlarge the diameter of the tube-shaped body and place an outer peripheral face of the tube-shaped body in contact with a hole wall of the through hole, and after enlarging the diameter, joining together a roll-overlap portion of the metal sheet that has been rolled into a roll shape.

TECHNICAL FIELD

The present invention relates to a heat exchanger manufacturing methodand a diameter enlargement tool.

BACKGROUND ART

Japanese Patent Application Laid-Open (JP-A) No. 2011-257084 describes amethod of inserting a tube-shaped body (heat transfer tube) formed byextruding aluminum in a tube shape through insertion holes formed infins, and then inserting a diameter enlargement tool (pipe enlargementtool) inside the tube-shaped body to enlarge the external diameter ofthe tube-shaped body.

SUMMARY OF INVENTION Technical Problem

However, in the method described in JP-A No. 2011-257084, the diameterenlargement tool is used to stretch the tube-shaped body in thecircumferential direction (stretch around the perimeter) in order toenlarge the external diameter, and so a large load is required toenlarge the diameter of the tube-shaped body.

In consideration of the above circumstances, an object of the presentinvention is to provide a heat exchanger manufacturing method and adiameter enlargement tool enabling a reduction in the load required toenlarge the diameter of the tube-shaped body.

Solution to Problem

A heat exchanger manufacturing method of a first aspect of the presentinvention includes a forming process of rolling a metal sheet into aroll shape to form a tube-shaped body, a diameter enlargement process ofinserting the tube-shaped body through a through hole formed at a metalfin, and loosening the metal sheet that has been rolled into a rollshape to enlarge the diameter of the tube-shaped body and place an outerperipheral face of the tube-shaped body in contact with a hole wall ofthe through hole, and a joining process of, after the diameterenlargement process, joining together a roll-overlap portion of themetal sheet that has been rolled into a roll shape.

In the heat exchanger manufacturing method of the first aspect, themetal sheet is rolled up into a roll shape to form the tube-shaped body,and the metal sheet rolled up into a roll shape is loosened to enlargethe diameter of the tube-shaped body. This enables the load required toenlarge the diameter of the tube-shaped body to be reduced compared to aconfiguration where an extrusion-formed heat transfer tube is stretchedin the circumferential direction (stretched around the perimeter) toenlarge the diameter.

A heat exchanger manufacturing method of a second aspect of the presentinvention is the heat exchanger manufacturing method of the first aspectin which, in the diameter enlargement process, a diameter enlargementtool, with an external diameter that is larger than an internal diameterof the tube-shaped body prior to diameter enlargement, is insertedinside the tube-shaped body to forcibly loosen the metal sheet that hasbeen rolled into a roll shape and enlarge the diameter of thetube-shaped body.

In the heat exchanger manufacturing method of the second aspect, in thediameter enlargement process, the diameter enlargement tool, with anexternal diameter that is larger than the internal diameter of thetube-shaped body prior to diameter enlargement, is inserted inside thetube-shaped body pre-diameter enlargement to forcibly loosen the metalsheet rolled up into a roll shape and enlarge the diameter of thetube-shaped body. Namely, employing the diameter enlargement tool withan external diameter larger than the internal diameter of thetube-shaped body pre-diameter enlargement enables the diameter of thetube-shaped body to be enlarged in a simple manner.

A heat exchanger manufacturing method of a third aspect of the presentinvention is the heat exchanger manufacturing method of the secondaspect in which, the metal sheet has an undulating portion formed on onesheet face and, in the forming process, the metal sheet is rolled into aroll shape to form the tube-shaped body with the undulating portion atan inner side thereof.

In the heat exchanger manufacturing method of the third aspect, themetal sheet is rolled up into a roll shape with the undulating portionformed on the one face on the inside to form the tube-shaped body withthe undulating portion at an inner peripheral face. Forming theundulating portion in this manner increases the surface area of theinner peripheral face of the tube-shaped body, improving heat transferefficiency between the tube-shaped body and fluid passing through insidethe tube-shaped body.

Note that the heat exchanger manufacturing method described aboveenables a reduction in the load required to enlarge the diameter of thetube-shaped body, thereby enabling deformation (squashing deformation)of the undulating portion formed at the inner peripheral face of thetube-shaped body to be suppressed when using the diameter enlargementtool to enlarge the diameter of the tube-shaped body. This enables heattransfer efficiency to be secured between the tube-shaped body and thefluid passing through inside the tube-shaped body.

A heat exchanger manufacturing method of a fourth aspect of the presentinvention is the heat exchanger manufacturing method of either thesecond aspect or the third aspect in which the metal sheet is configuredby aluminum.

In the heat exchanger manufacturing method of the fourth aspect, themetal sheet rolled up into a roll shape to form the tube-shaped body isconfigured by aluminum, thereby enabling a reduction in weight and areduction in costs, while securing heat transfer efficiency between thetube-shaped body and the fluid passing through inside the tube-shapedbody. Moreover, configuring the metal sheet by aluminum enables the loadrequired to enlarge the diameter of the tube-shaped body to be reducedcompared to cases in which the metal sheet is configured by a materialthat deforms less readily, such as a steel sheet. Deformation (squashingdeformation) of an undulating portion formed at the inner peripheralface of the tube-shaped body can accordingly be further suppressed whenenlarging the diameter of the tube-shaped body with the diameterenlargement tool.

A heat exchanger manufacturing method of a fifth aspect of the presentinvention is the heat exchanger manufacturing method of any one of thesecond aspect to the fourth aspect in which the diameter enlargementtool includes a circular column-shaped main body that is inserted insidethe tube-shaped body, ribs that are provided at intervals in acircumferential direction around an outer peripheral face of the mainbody, that project outward from the main body outer peripheral face,that extend from an end portion of the main body at an insertiondirection side toward an opposite side to the insertion direction, andthat contact an inner peripheral face of the tube-shaped body, andinclined portions that are formed at insertion direction leading endportions of the ribs, and that have a projection height from the mainbody outer peripheral face that gradually increases toward the oppositeside to the insertion direction.

In the heat exchanger manufacturing method of the fifth aspect, the ribsof the diameter enlargement tool contact the inner peripheral face ofthe tube-shaped body, thereby enabling a reduction in the contactsurface area between the diameter enlargement tool and the innerperipheral face of the tube-shaped body, enabling a reduction inresistance from deformation of the tube-shaped body when inserting thediameter enlargement tool into the tube-shaped body. The load requiredto insert the diameter enlargement tool into the tube-shaped body canaccordingly be reduced.

The leading end portions of the ribs in the insertion direction areformed with the inclined portions whose projection height from the outerperipheral face of the main body gradually increases on progressiontoward the opposite side to the insertion direction. The inclinedportions accordingly act as guides for enlarging the diameter of thetube-shaped body when the diameter enlargement tool is inserted into thetube-shaped body pre-diameter enlargement. This enables smootherinsertion of the diameter enlargement tool into the tube-shaped bodythan a rib configuration that does not include the inclined portions.

A heat exchanger manufacturing method of a sixth aspect of the presentinvention is the heat exchanger manufacturing method of the fifth aspectin which the ribs extend in a spiral shape toward the opposite side ofthe main body to the insertion direction, with the direction of thespiral being set as an opposite direction to a roll-up direction of themetal sheet that has been rolled into a roll shape.

In the heat exchanger manufacturing method of the sixth aspect, the ribsextend in a spiral shape toward the side of the main body opposite tothe insertion direction, with the direction of the spiral set as theopposite direction to the roll-up direction of the metal sheet rolled upinto a roll shape. The metal sheet rolled up into a roll shape isaccordingly imparted with force from the ribs in the opposite directionto the roll-up direction and is loosened when the diameter enlargementtool is inserted into the tube-shaped body. The load required to enlargethe diameter of the tube-shaped body can accordingly be reduced.

A heat exchanger manufacturing method of a seventh aspect of the presentinvention is the heat exchanger manufacturing method of the fifth aspectin which the ribs extend in straight line shapes toward the oppositeside of the main body to the insertion direction, and an intervalbetween respective contact portions, at which two of the ribs disposedon either side of a peripheral inside edge portion of the metal sheetthat has been rolled into a roll shape contact the inner peripheral faceof the tube-shaped body, widens toward the opposite side to theinsertion direction.

In the heat exchanger manufacturing method of the seventh aspect, theseparation between respective contact portions where two of the ribsdisposed on each side of a peripheral inside end portion of the metalsheet rolled up into a roll shape contact the inner peripheral face ofthe tube-shaped body widens on progression toward the opposite side tothe insertion direction. When the diameter enlargement tool is insertedinto the tube-shaped body, the peripheral inside edge portion of themetal sheet rolled up into a roll shape is accordingly imparted withforce from the two ribs in the opposite direction to the roll-updirection, and moves in the circumferential direction of the tube-shapedbody, thereby loosening the metal sheet rolled up into a roll shape.This enables the load required to enlarge the diameter of thetube-shaped body to be reduced.

A diameter enlargement tool of an eighth aspect of the present inventionis a diameter enlargement tool to enlarge the diameter of a tube-shapedbody formed by rolling a metal sheet into a roll shape, the diameterenlargement tool including a circular column-shaped main body that isinserted inside the tube-shaped body, ribs that are provided atintervals in a circumferential direction around an outer peripheral faceof the main body, that project outward from the main body outerperipheral face, that extend from an end portion of the main body at aninsertion direction side toward an opposite side to the insertiondirection, and that contact an inner peripheral face of the tube-shapedbody, and inclined portions that are formed at insertion directionleading end portions of the ribs, and that have a projection height fromthe main body outer peripheral face that gradually increases toward theopposite side to the insertion direction, wherein an external diameterof the diameter enlargement tool is larger than an internal diameter ofthe tube-shaped body.

In the diameter enlargement tool of the eighth aspect, the externaldiameter of the diameter enlargement tool is larger than the internaldiameter of the tube-shaped body, such that inserting the diameterenlargement tool into the tube-shaped body forcibly loosens the metalsheet rolled up into a roll shape and enlarges the diameter of thetube-shaped body. Note that during insertion of the diameter enlargementtool, the ribs contact the inner peripheral face of the tube-shapedbody, thereby enabling a reduction in the contact surface area betweenthe diameter enlargement tool and the inner peripheral face of thetube-shaped body. Resistance due to deformation of the tube-shaped bodywhen inserting the diameter enlargement tool into the tube-shaped bodycan accordingly be reduced. This enables a reduction in the loadrequired to insert the diameter enlargement tool into the tube-shapedbody. The load required to enlarge the diameter of the tube-shaped bodycan be reduced as a result.

Advantageous Effects of Invention

As described above, the heat exchanger manufacturing method and thediameter enlargement tool of the present invention enable a reduction inthe load required to enlarge the diameter of a tube-shaped body.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-section taken along the axial direction of atube-shaped body to explain a diameter enlargement process of a heatexchanger manufacturing method of a first exemplary embodiment.

FIG. 2 is a cross-section taken along line 2X-2X in FIG. 1.

FIG. 3 is a cross-section taken along line 3X-3X in FIG. 1.

FIG. 4A is a perspective view illustrating a diameter enlargement toolemployed in a heat exchanger manufacturing method of the first exemplaryembodiment.

FIG. 4B is a front view of the diameter enlargement tool illustrated inFIG. 4A.

FIG. 4C is a side view of the diameter enlargement tool illustrated inFIG. 4A.

FIG. 5 is a cross-section taken along the axial direction of atube-shaped body of a heat exchanger manufactured using a heat exchangermanufacturing method of the first exemplary embodiment.

FIG. 6A is a perspective view illustrating a first modified example of adiameter enlargement tool employed in the first exemplary embodiment.

FIG. 6B is a front view of the diameter enlargement tool of the firstmodified example illustrated in FIG. 6A.

FIG. 6C is a side view of the diameter enlargement tool of the firstmodified example illustrated in FIG. 6A.

FIG. 7A is a perspective view illustrating a second modified example ofa diameter enlargement tool employed in the first exemplary embodiment.

FIG. 7B is a front view of the diameter enlargement tool of the secondmodified example illustrated in FIG. 7A.

FIG. 7C is a side view of the diameter enlargement tool of the secondmodified example illustrated in FIG. 7A.

FIG. 8A is a perspective view illustrating a third modified example of adiameter enlargement tool employed in the first exemplary embodiment.

FIG. 8B is a front view of the diameter enlargement tool of the thirdmodified example illustrated in FIG. 8A.

FIG. 8C is a side view of the diameter enlargement tool of the thirdmodified example illustrated in FIG. 8A.

FIG. 9 is a cross-section taken along an axis-orthogonal direction of atube-shaped body employed in a heat exchanger of a heat exchangermanufacturing method of a second exemplary embodiment.

FIG. 10 is a cross-section taken along an axis-orthogonal direction(corresponding to a cross-section taken along line 2X-2X of FIG. 1) of atube-shaped body pre-diameter enlargement to explain a diameterenlargement process of a heat exchanger manufacturing method of thesecond exemplary embodiment.

FIG. 11 is a cross-section taken along an axis-orthogonal direction(corresponding to a cross-section taken along line 3X-3X of FIG. 1) of atube-shaped body after diameter enlargement to explain a diameterenlargement process of the heat exchanger manufacturing methodillustrated in FIG. 10.

DESCRIPTION OF EMBODIMENTS

Explanation follows regarding exemplary embodiments of a heat exchangermanufacturing method and a diameter enlargement tool according to thepresent invention, with reference to the drawings.

First Exemplary Embodiment

FIG. 5 illustrates a heat exchanger 20 manufactured by a heat exchangermanufacturing method of a first exemplary embodiment. The heat exchanger20 of the present exemplary embodiment is installed in an airconditioner, and is employed in heat exchange with a fluid employed in aheat exchange section of the air conditioner. Note that the presentinvention is not limited to such a configuration, and the heat exchanger20 may be installed in a refrigerator and employed to cool a coolant (anexample of a fluid) employed in a cooling section of the refrigerator,or may be installed to a vehicle and employed to cool coolant water (anexample of a fluid) in an engine cooling device. Namely, the heatexchanger 20 of the present exemplary embodiment may be applied to anyequipment that performs heat exchange with a fluid.

As illustrated in FIG. 5, the heat exchanger 20 of the present exemplaryembodiment includes a heat transfer tube 30 and fins 40. The heattransfer tube 30 is an example of a tube-shaped body of the presentinvention.

As illustrated in FIG. 2 and FIG. 3, the heat transfer tube 30 is formedby bending a single metal sheet 31. Specifically, the heat transfer tube30 is formed by rolling up the single metal sheet 31 into a roll shapeand joining together at a roll-overlap portion. The heat transfer tube30 of the present exemplary embodiment is a double-walled rolled tubeconfigured by rolling the metal sheet 31 around twice. In the heattransfer tube 30, part of an inner face 31B of the metal sheet 31 rolledup into a roll shape configures a tube inner face 30B, and part of anouter face 31A of the metal sheet 31 rolled up into a roll shapeconfigures a tube outer face 30A. The tube outer face 30A indicates theouter peripheral face of the heat transfer tube 30, and the tube innerface 30B indicates the inner peripheral face of the heat transfer tube30. In the drawings, the axial direction of the heat transfer tube 30 isindicated by the direction of arrow A.

The inner face 31B of the metal sheet 31 rolled up into a roll shape isformed with an inside stepped face 32B between a peripheral inside edgeportion 31C and a peripheral outside edge portion 31D. The edge portion31C of the metal sheet 31 rolled up into a roll shape is joined to theinside stepped face 32B.

The outer face 31A of the metal sheet 31 rolled up into a roll shape isformed with an outside stepped face 32A between the edge portion 31C andthe edge portion 31D. The edge portion 31D of the metal sheet 31 rolledup into a roll shape is joined to the outside stepped face 32A.

In a manufacturing method of the heat exchanger 20 of the presentexemplary embodiment, described later, an intermediate portion (roll-updirection intermediate portion) between the edge portion 31C and theedge portion 31D of the metal sheet 31 rolled up into a roll shape isbent into a substantially crank shape, forming a stepped portion 32. Oneface (the face configuring the inner face 31B) of the thus formedstepped portion 32 configures the inside stepped face 32B, and the otherface (the face configuring the outer face 31A) configures the outsidestepped face 32A.

The metal sheet 31 forming the heat transfer tube 30 is a metal sheetwith a core formed from a metal material affixed with a covering memberformed from a metal material with a lower melting point than the core,namely a clad sheet. In the present exemplary embodiment, the metalsheet 31 is configured by aluminum. Specifically, the metal sheet 31 isformed by affixing a covering member formed from an aluminum alloy (forexample, aluminum impregnated with silicon) to a core formed from purealuminum. The covering member forms the outer face 31A of the metalsheet 31 rolled up into a roll shape. The covering member is moreoveremployed as a joining material (brazing filler) for joining together theroll-overlap portion of the metal sheet 31 rolled up into a roll shape.The core forms the inner face 31B of the metal sheet 31 rolled up into aroll shape.

Note that in the present exemplary embodiment, the metal sheet 31 isconfigured by aluminum, however the present invention is not limited tosuch a configuration, and the metal sheet 31 may be configured from ametal material such as copper or iron.

As illustrated in FIG. 5, the fins 40 are configured by forming a metalmaterial (for example aluminum) into plate shapes. The fins 40 areformed with through holes 42 penetrating in the plate thicknessdirection. Specifically, the through holes 42 are formed in the fins 40by burring. The heat transfer tube 30 is inserted through the throughholes 42, and the tube outer face 30A, that is the outer peripheral faceof the heat transfer tube 30, is joined to hole walls 42A. Note that inthe present exemplary embodiment, the tube outer face 30A of the heattransfer tube 30 is joined to hole walls 42A configuring inner walls ofring shaped stand-out portions 44 formed by burring the fins 40.

Next, detailed explanation follows regarding the heat exchanger 20. Inthe heat exchanger 20, plural of the heat transfer tubes 30 are arrangedparallel to each other in a row, and end portions of adjacent heattransfer tubes 30 are coupled together by U-shaped tube connectors. Eachof the heat transfer tubes 30 is inserted through respective throughholes 42 of the plural fins 40, and the respective tube outer faces 30Aare joined to the respective hole walls 42A.

Explanation follows regarding a manufacturing method of the heatexchanger 20 according to the first exemplary embodiment of the presentinvention.

Forming Process

First, the flat plate shaped metal sheet 31 is prepared, with thecovering member affixed to the core. The metal sheet 31 is rolled upinto a roll shape to form the heat transfer tube 30 (pre-diameterenlargement heat transfer tube) that is an example of a tube-shaped body(see FIG. 2). Specifically, the metal sheet 31 is rolled up into a rollshape using a roll forming machine, namely by roll forming, to form theheat transfer tube 30. In the forming process, the metal sheet 31 isrolled up into a roll shape such that the external diameter of the heattransfer tube 30 is smaller than the diameter of the through holes 42formed in the fins 40 (see FIG. 1).

Diameter Enlargement Process

Next, the metal sheet 31 rolled up into a roll shape is inserted throughthe through holes 42 formed in the fins 40. The metal sheet 31 rolled upinto a roll shape is then loosened to enlarge the diameter of the heattransfer tube 30, placing the tube outer face 30A of the heat transfertube 30 in contact with the hole walls 42A of the through holes 42 ofthe fins 40. Specifically, as illustrated in FIG. 1, a diameterenlargement tool 50 with a larger external diameter than the internaldiameter of the heat transfer tube 30 pre-diameter enlargement isinserted inside the pre-diameter enlargement heat transfer tube 30,forcibly loosening the metal sheet 31 rolled up into a roll shape toenlarge the diameter of the heat transfer tube 30. The external diameterof the diameter enlargement tool 50 is set at a size to enlarge thediameter of the heat transfer tube 30 far enough for the tube outer face30A to contact the hole walls 42A.

During diameter enlargement of the heat transfer tube 30, as illustratedin FIG. 3, the stepped portion 32 is formed between the edge portion 31Cand the edge portion 31D of the metal sheet 31 rolled up into a rollshape. When this is performed, the edge portion 31C is disposed facingthe inside stepped face 32B of the stepped portion 32, and the edgeportion 31D is disposed facing the outside stepped face 32A of thestepped portion 32.

Joining Process

Next, the metal sheet 31 rolled up into a roll shape is heated togetherwith the fins 40, melting the covering member, and then the coveringmember is cooled and hardened in a close contact state of theroll-overlap portion of the metal sheet 31 rolled up into a roll shape,thereby joining (brazing) the roll-overlap portion of the metal sheet 31rolled up into a roll shape. When this is performed, the covering memberforming the outer periphery of the metal sheet 31 rolled up into a rollshape is also joined to the hole walls 42A of the through holes 42. Theheat exchanger 20 is thereby formed.

Next, explanation follows regarding the diameter enlargement tool 50employed in the manufacturing method of the heat exchanger 20 of thepresent exemplary embodiment.

As illustrated in FIG. 1 and FIG. 4A to FIG. 4C, the diameterenlargement tool 50 is configured including a circular column-shapedmain body 52 that is inserted inside the heat transfer tube 30, ribs 54provided at an outer peripheral face 52A of the main body 52, andinclined portions 56 formed at insertion direction leading end portionsof the ribs 54. The insertion direction of the main body 52 is the samedirection as the insertion direction of the diameter enlargement tool50, and the insertion direction of the main body 52 is indicated by thedirection of arrow B in the drawings.

The ribs 54 project out from the outer peripheral face 52A of the mainbody 52, and extend from the insertion direction leading end side of themain body 52 toward the opposite side to the insertion direction. Pluralof the ribs 54 are provided at intervals around the circumferentialdirection of the main body 52 (the direction indicated by arrow C in thedrawings). Apex portions 54A of the ribs 54 are configured so as tocontact the tube inner face 30B of the heat transfer tube 30. Theexternal diameter of the diameter enlargement tool 50 refers to theexternal diameter of a circle that passes through the locations of theribs 54 most distant from the axial center of the main body 52 (portionsof the apex portions 54A).

The ribs 54 extend in straight line shapes toward the opposite side tothe insertion direction of the main body 52. A separation L betweenrespective contact portions where two of the ribs 54, disposed on eachside of the edge portion 31C of the metal sheet 31 rolled up into a rollshape, contact the tube inner face 30B of the heat transfer tube 30widens on progression toward the opposite side to the insertiondirection of the main body 52.

The inclined portions 56 are configured such that their projectionheight from the outer peripheral face 52A of the main body 52 becomesgradually higher on progression toward the opposite side to theinsertion direction of the main body 52.

A rod 58, extending from a drive device that inserts the main body 52into the heat transfer tube 30, is coupled to the diameter enlargementtool 50.

Explanation follows regarding operation and advantageous effects of themanufacturing method of the heat exchanger 20 of the present exemplaryembodiment.

In the manufacturing method of the heat exchanger 20 of the presentexemplary embodiment, the metal sheet 31 is rolled up into a roll shapeto form the heat transfer tube 30, and then the metal sheet 31 rolled upinto a roll shape is loosened to enlarge the diameter of the heattransfer tube 30. The load required to enlarge the diameter of the heattransfer tube 30 can accordingly be reduced compared to in aconfiguration where an extrusion-formed extruded heat transfer tube isstretched in the circumferential direction (stretched around theperimeter) to enlarge the diameter.

Specifically, in the diameter enlargement process of the manufacturingmethod of the heat exchanger 20, the diameter enlargement tool 50 thathas a larger external diameter than the internal diameter of the heattransfer tube 30 pre-diameter enlargement is inserted inside the heattransfer tube 30, and the metal sheet 31 rolled up into a roll shape isforcibly loosened to enlarge the diameter of the heat transfer tube 30.Namely, employing the diameter enlargement tool 50 with a largerexternal diameter than the internal diameter of the heat transfer tube30 pre-diameter enlargement enables simple diameter enlargement in theheat transfer tube 30.

During diameter enlargement of the heat transfer tube 30, the ribs 54 ofthe diameter enlargement tool 50 contact the tube inner face 30B of theheat transfer tube 30, thereby enabling a reduction in the contactsurface area between the diameter enlargement tool 50 and the tube innerface 30B of the heat transfer tube 30, and enabling a reduction inresistance due to deformation of the heat transfer tube 30 when thediameter enlargement tool 50 is inserted into the heat transfer tube 30.The load required to insert the diameter enlargement tool 50 into theheat transfer tube 30 can accordingly be reduced.

The leading end portions of the ribs 54 in the insertion direction ofthe main body 52 are formed with the inclined portions 56 whoseprojection height from the outer peripheral face 52A of the main body 52gradually increases on progression toward the opposite side to theinsertion direction. Accordingly, during insertion of the diameterenlargement tool 50 into the heat transfer tube 30 pre-diameterenlargement, the inclined portions 56 act as guides for the diameterenlargement of the heat transfer tube 30. The diameter enlargement tool50 can accordingly be inserted smoothly into the heat transfer tube 30.

Moreover, during diameter enlargement of the heat transfer tube 30, theseparation L between the respective contact portions where the two ribs54 disposed on each side of the edge portion 31C of the metal sheet 31rolled up into a roll shape contact the tube inner face 30B of the heattransfer tube 30 widens on progression toward the opposite side of themain body 52 to the insertion direction. Accordingly, when the diameterenlargement tool 50 is inserted into the heat transfer tube 30, the edgeportion 31C of the metal sheet 31 rolled up into a roll shape isimparted with force from the two ribs 54 in the opposite direction tothe roll-up direction and moves in the heat transfer tube 30circumferential direction (indicated by the arrow D in the drawings),thereby loosening the metal sheet 31 rolled up into a roll shape. Thisenables a reduction in the load required for diameter enlargement of theheat transfer tube 30.

In the manufacturing method of the heat exchanger 20, the metal sheet 31rolled up into a roll shape to form the heat transfer tube 30 isconfigured by aluminum, thereby enabling a reduction in weight andreduction in costs of the heat exchanger 20 while securing heat transferefficiency between the heat transfer tube 30 and the fluid passingthrough the heat transfer tube 30. Configuring the metal sheet 31 byaluminum enables, for example, a reduction in the load required fordiameter enlargement of the heat transfer tube 30 in comparison to whenthe metal sheet 31 is formed from a material that does not deform soreadily, such as steel sheet.

In the present exemplary embodiment, the diameter enlargement tool 50 isused to enlarge the diameter of the heat transfer tube 30 formed byrolling up the metal sheet 31 into a roll shape, however the presentinvention is not limited to such a configuration. For example, thediameter of the heat transfer tube 30 may be enlarged using a diameterenlargement tool 60 of a first modified example, a diameter enlargementtool 70 of a second modified example, or a diameter enlargement tool 80of a third modified example of the diameter enlargement tool 50,respectively described below. Note that the diameter enlargement tool 60of the first modified example, the diameter enlargement tool 70 of thesecond modified example, and the diameter enlargement tool 80 of thethird modified example may also be employed in the manufacturing methodof a heat exchanger 22 of a second exemplary embodiment, describedlater.

As illustrated in FIG. 6A to FIG. 6C, in the diameter enlargement tool60 of the first modified example, ribs 64 projecting out from the outerperipheral face 52A of the main body 52 extend in straight line shapesfrom an end portion of the main body 52 on the insertion direction sidetoward the opposite side to the insertion direction. Plural of the ribs64 are provided at uniform separations around the circumferentialdirection of the main body 52. Accordingly, during insertion of thediameter enlargement tool 60 into the heat transfer tube 30 pre-diameterenlargement, the diameter enlargement tool 60 can be inserted into theheat transfer tube 30 pre-diameter enlargement without limitation to theposition of the ribs 64 of the diameter enlargement tool 60. Thecomplexity of the heat transfer tube 30 diameter enlargement operationcan accordingly be lessened. Note that the reference numeral 64A in FIG.6A to FIG. 6C indicates the apex portions of the ribs 64.

As illustrated in FIG. 7A to FIG. 7C, in the diameter enlargement tool70 of the second modified example, ribs 74 projecting out from the outerperipheral face 52A of the main body 52 extend in a spiral shape from anend portion of the main body 52 on the insertion direction side towardthe opposite side to the insertion direction (specifically, in a spiralshape around the outer peripheral face 52A of the main body 52). Thespiral direction of the ribs 74 is the opposite direction to the roll-updirection of the metal sheet 31 rolled up into a roll shape. Plural ofthe ribs 74 are provided at uniform separations around thecircumferential direction of the main body 52. Note that on insertion ofthe diameter enlargement tool 70 into the heat transfer tube 30, themetal sheet 31 rolled up into a roll shape is imparted with force fromthe spiral shaped ribs 74 in the opposite direction to the roll-updirection and is loosened. This enables a reduction in the load requiredto enlarge the diameter of the heat transfer tube 30. Note that thereference numeral 74A in FIG. 7A to FIG. 7C indicates the apex portionsof the ribs 74.

As illustrated in FIG. 8A to FIG. 8C, in the diameter enlargement tool80 of the third modified example, ribs 84 projecting out from the outerperipheral face 52A of the main body 52 extend in straight line shapesfrom an end portion of the main body 52 on the insertion direction sidetoward the opposite side to the insertion direction. The width (thelength around the circumferential direction of the main body 52) of apexportions 84A of the ribs 84 becomes gradually wider on progressiontoward the opposite side to the insertion direction of the main body 52.Note that when the diameter enlargement tool 80 is inserted into theheat transfer tube 30 pre-diameter enlargement, narrow-width portions ofthe apex portions 84A of the ribs 84 contact the tube inner face 30B ofthe heat transfer tube 30 first, enabling resistance due to deformationof the heat transfer tube 30 to be lowered, and enabling a reduction inthe load required for insertion. Wider-width portions of the apexportions 84A then contact the tube outer face 30A of the heat transfertube 30, enabling substantially uniform enlargement around thecircumference of the tube inner face 30B of the heat transfer tube 30.

Second Exemplary Embodiment

FIG. 9 illustrates a heat transfer tube 90 of the heat exchanger 22manufactured by a heat exchanger manufacturing method of a secondexemplary embodiment. Note that in the present exemplary embodiment,configuration similar to that of the first exemplary embodiment isallocated the same reference numerals, and further explanation thereofis omitted.

With the exception of the configuration of the heat transfer tube 90,the heat exchanger 22 of the present exemplary embodiment is of similarconfiguration to the heat exchanger 20 of the first exemplaryembodiment.

As illustrated in FIG. 9, an inner peripheral face (referred to below asthe “tube inner face 90B”) of the heat transfer tube 90 is formed withan undulating portion 92. The undulating portion 92 is formed oversubstantially the entire tube inner face 90B. The heat transfer tube 90of the present exemplary embodiment is an example of a tube-shaped bodyof the present invention.

The heat transfer tube 90 is formed by rolling up a metal sheet 31formed with the undulating portion 92 into a roll shape, and joining ata roll-overlap portion. The heat transfer tube 90 of the presentexemplary embodiment is a double-walled rolled tube configured byrolling the metal sheet 31 around twice. In the heat transfer tube 90,part of an inner face 31B of the metal sheet 31 rolled up into a rollshape configures the tube inner face 90B, and part of an outer face 31Aof the metal sheet 31 rolled up into a roll shape configures a tubeouter face 90A. Other than being formed with the undulating portion 92,the metal sheet 31 is of similar configuration to the metal sheet 31 ofthe first exemplary embodiment.

As illustrated in FIG. 9, the undulating portion 92 is configured bygrooves 92A indented toward the radial direction outside of the heattransfer tube 90, formed at intervals around the circumferentialdirection of the heat transfer tube 90, and extending in a directionintersecting with the axial direction of the heat transfer tube 90 (adirection at an angle in the present exemplary embodiment), and byridges 92B that are formed between adjacent grooves 92A to formprojections toward the radial direction inside of the heat transfer tube90. Note that the undulating portion of the present invention is notlimited to such a configuration. For example, an undulating portion maybe configured by forming plural projections and plural recesses on thetube inner face 90B.

Next, explanation follows regarding a manufacturing method of the heatexchanger 22 of the present exemplary embodiment.

Forming Process

First, the flat plate shaped metal sheet 31 is prepared with thecovering member affixed to the core, and the undulating portion 92 isformed to one face of the metal sheet 31 (the face formed by the core).Note that the undulating portion 92 is formed to the one face of themetal sheet 31 in a range corresponding to the tube inner face 90B.

Next, the metal sheet 31 formed on the one face with the undulatingportion 92 is rolled up into a roll shape with the undulating portion 92on the inside to form the heat transfer tube 90 that is an example of atube-shaped body (see FIG. 10).

Next, as illustrated in FIG. 10 and FIG. 11, the diameter enlargementtool 50 is used to perform a diameter enlargement process similar tothat of the first exemplary embodiment, thereby enlarging the diameterof the heat transfer tube 90.

A joining process similar to that of the first exemplary embodiment isperformed in order to form the heat exchanger 22 of the presentexemplary embodiment.

Explanation follows regarding operation and advantageous effects of themanufacturing method of the heat exchanger 22 of the present exemplaryembodiment.

In the manufacturing method of the heat exchanger 22, the metal sheet 31is rolled up into a roll shape, with the undulating portion 92 formed tothe one face on the inside, thereby forming the heat transfer tube 90with the undulating portion 92 formed at the tube inner face 90B.Forming the undulating portion 92 in this manner increases the surfacearea of the tube inner face 90B of the heat transfer tube 90, raisingthe heat transfer efficiency between the heat transfer tube 90 and thefluid passing through inside the heat transfer tube 90.

Note that since the manufacturing method of the heat exchanger 22enables a reduction in the load required to enlarge the diameter of theheat transfer tube 90, similarly to in the first exemplary embodiment,deformation (squashing deformation) of the undulating portion 92 formedto the tube inner face 90B can be suppressed when using the diameterenlargement tool 50 to enlarge the diameter of the heat transfer tube90. Heat transfer efficiency between the heat transfer tube 90 and thefluid passing through inside the heat transfer tube 90 can accordinglybe secured.

In the first exemplary embodiment, the stepped portion 32 is formed tothe metal sheet 31 during the diameter enlargement process, however thepresent invention is not limited to such a configuration. For example,the stepped portion 32 may be formed to the metal sheet 31 in advance,prior to the diameter enlargement process. Note that such aconfiguration, in which the stepped portion 32 is formed to the metalsheet 31 in advance prior to the diameter enlargement process, may alsobe applied to the second exemplary embodiment.

In the first exemplary embodiment, the metal sheet 31 is a clad sheetconfigured by the core and the covering member, however the presentinvention is not limited thereto, and the metal sheet 31 may be a metalsheet configured by the core alone. In such cases, configuration may bemade such that molten joining material (brazing filler) is injected intoa gap at the roll-overlap portion of the metal sheet 31 of the heattransfer tube 30 after diameter enlargement to join together theroll-overlap portion of the metal sheet 31. Moreover, one or both facesof the fins 40 may be formed from an aluminum alloy (brazing filler),and heated together with the heat transfer tube 30 after diameterenlargement such that the roll-overlap portion of the metal sheet 31 isjoined by the melted aluminum alloy. Such a configuration may also beapplied to the second exemplary embodiment.

In the first exemplary embodiment, the heat transfer tube 30 is adouble-walled rolled tube configured by rolling the metal sheet 31around twice, however the present invention is not limited to such aconfiguration, and the metal sheet 31 may be rolled around more thantwice to configure a multi-ply rolled tube. Such a configuration mayalso be applied to the heat transfer tube 90 of the second exemplaryembodiment.

Explanation has been given above regarding exemplary embodiments of thepresent invention, however these exemplary embodiments are merelyexamples, and various modifications may be implemented within a rangenot departing from the spirit of the present invention. Obviously, thescope of rights encompassed by the present invention is not limited bythese exemplary embodiments.

The disclosure of Japanese Patent Application No. 2014-014650, filed onJan. 29, 2014, is incorporated in its entirety by reference herein.

All cited documents, patent applications and technical standardsmentioned in the present specification are incorporated by reference inthe present specification to the same extent as if the individual citeddocument, patent application, or technical standard was specifically andindividually indicated to be incorporated by reference.

1. A heat exchanger manufacturing method, comprising: rolling a metalsheet into a roll shape to form a tube-shaped body; inserting thetube-shaped body through a through hole formed at a metal fin, andloosening the metal sheet that has been rolled into a roll shape toenlarge the diameter of the tube-shaped body and place an outerperipheral face of the tube-shaped body in contact with a hole wall ofthe through hole; and after enlarging the diameter, joining together aroll-overlap portion of the metal sheet that has been rolled into a rollshape.
 2. The heat exchanger manufacturing method of claim 1, wherein,in the enlarging of the diameter, inserting a diameter enlargement tool,with an external diameter that is larger than an internal diameter ofthe tube-shaped body prior to diameter enlargement, inside thetube-shaped body to forcibly loosen the metal sheet that has been rolledinto a roll shape and enlarge the diameter of the tube-shaped body. 3.The heat exchanger manufacturing method of claim 2, wherein the metalsheet has an undulating portion formed on one sheet face and, in theforming of the tube-shaped body, rolling the metal sheet into a rollshape to form the tube-shaped body with the undulating portion at aninner side thereof.
 4. The heat exchanger manufacturing method of claim2, comprising configuring the metal sheet by aluminum.
 5. The heatexchanger manufacturing method of claim 2, wherein the diameterenlargement tool comprises: a circular column-shaped main body that isinserted inside the tube-shaped body; ribs that are provided atintervals in a circumferential direction around an outer peripheral faceof the main body, that project outwardly from the main body outerperipheral face, that extend from an end portion of the main body at aninsertion direction side toward an opposite side to the insertiondirection, and that contact an inner peripheral face of the tube-shapedbody; and inclined portions that are formed at insertion directionleading end portions of the ribs, and that have a projection height fromthe main body outer peripheral face that gradually increases toward theopposite side to the insertion direction.
 6. The heat exchangermanufacturing method of claim 5, wherein the ribs extend in a spiralshape toward the opposite side of the main body to the insertiondirection, with the direction of the spiral being set as an oppositedirection to a roll-up direction of the metal sheet that has been rolledinto a roll shape.
 7. The heat exchanger manufacturing method of claim5, wherein: the ribs extend in straight line shapes toward the oppositeside of the main body to the insertion direction; and an intervalbetween respective contact portions, at which two of the ribs disposedon either side of a peripheral inside edge portion of the metal sheetthat has been rolled into a roll shape contact the inner peripheral faceof the tube-shaped body, widens toward the opposite side to theinsertion direction.
 8. A diameter enlargement tool to enlarge thediameter of a tube-shaped body formed by rolling a metal sheet into aroll shape, the diameter enlargement tool comprising: a circularcolumn-shaped main body that is inserted inside the tube-shaped body;ribs that are provided at intervals in a circumferential directionaround an outer peripheral face of the main body, that project outwardfrom the main body outer peripheral face, that extend from an endportion of the main body at an insertion direction side toward anopposite side to the insertion direction, and that contact an innerperipheral face of the tube-shaped body; and inclined portions that areformed at insertion direction leading end portions of the ribs, and thathave a projection height from the main body outer peripheral face thatgradually increases toward the opposite side to the insertion direction,wherein an external diameter of the diameter enlargement tool is largerthan an internal diameter of the tube-shaped body.